Unicode C++
Unicode C++
PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)
See more SCard Examples
Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.Note: This functionality was introduced in Chilkat v9.5.0.87.
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#include <CkSCardW.h>
#include <CkJsonObjectW.h>
#include <CkStringBuilderW.h>
#include <CkStringTableW.h>
void ChilkatSample(void)
{
bool success = false;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
CkSCardW scard;
// First establish a context to the PC/SC Resource Manager
success = scard.EstablishContext(L"user");
if (success == false) {
wprintf(L"%s\n",scard.lastErrorText());
return;
}
// First we'll examine the state of all connected readers to see which have smartcards already inserted..
// Get JSON containing information about the smartcards currently inserted into readers.
// This also includes information about USB security tokens.
CkJsonObjectW json;
success = scard.FindSmartcards(json);
if (success == false) {
wprintf(L"%s\n",scard.lastErrorText());
return;
}
// When writing this example, I have 3 smart card readers plugged into my system.
// One of them has a smart card inserted.
// Here's the JSON returned by FindSmartcards...
// {
// "reader": [
// {
// "name": "Alcor Micro USB Smart Card Reader 0",
// "state": "empty"
// },
// {
// "name": "Generic Smart Card Reader Interface 0",
// "state": "present",
// "vendorName": "Generic",
// "serialNumber": "3230303730383138303030303030303030",
// "systemName": "Generic Smart Card Reader Interface 0",
// "card": {
// "atr": "3BFC180000813180459067464A00641606F2727E00E0",
// "windows": {
// "miniDriver": "tagliov70px.dll",
// "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
// "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
// }
// }
// },
// {
// "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
// "state": "empty"
// }
// ]
// }
json.put_EmitCompact(false);
wprintf(L"%s\n",json.emit());
wprintf(L" \n");
// We can iterate over the JSON to find the readers with a smart card already inserted..
const wchar_t *name = 0;
CkStringBuilderW sbState;
int i = 0;
int count_i = json.SizeOfArray(L"reader");
while (i < count_i) {
json.put_I(i);
name = json.stringOf(L"reader[i].name");
sbState.Clear();
json.StringOfSb(L"reader[i].state",sbState);
if (sbState.Contains(L"present",true) == true) {
wprintf(L"%s has a smart card inserted.\n",name);
}
else {
wprintf(L"%s does not have a smart card inserted.\n",name);
}
i = i + 1;
}
wprintf(L" \n");
// Now let's begin the code to wait for a change (where a smart card gets inserted or removed)
// Get the list of all readers.
CkStringTableW stReaders;
success = scard.ListReaders(stReaders);
if (success == false) {
wprintf(L"%s\n",scard.lastErrorText());
return;
}
// Show the reader names..
int numReaders = stReaders.get_Count();
i = 0;
while (i < numReaders) {
wprintf(L"%d: %s\n",i,stReaders.stringAt(i));
i = i + 1;
}
// Sample output from the above loop.
// 0: Alcor Micro USB Smart Card Reader 0
// 1: Generic Smart Card Reader Interface 0
// 2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
//
// Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
CkJsonObjectW json2;
success = scard.GetStatusChange(30000,stReaders,json2);
if (success == false) {
wprintf(L"%s\n",scard.lastErrorText());
return;
}
wprintf(L" \n");
// Let's see what happened...
json2.put_EmitCompact(false);
wprintf(L"%s\n",json2.emit());
wprintf(L" \n");
// This is what json2 contains.
// A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
// The "numChanged" indicates that one reader's status changed.
// The "changed":true indicates the reader that changed. The state is now "present".
// {
// "numChanged": 1,
// "reader": [
// {
// "name": "Alcor Micro USB Smart Card Reader 0",
// "changed": false,
// "state": "empty"
// },
// {
// "name": "Generic Smart Card Reader Interface 0",
// "changed": false,
// "state": "present",
// "atr": "3BFC180000813180459067464A00641606F2727E00E0"
// },
// {
// "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
// "changed": true,
// "state": "present",
// "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
// }
// ]
// }
// Find the reader that changed...
bool changed;
const wchar_t *state = 0;
const wchar_t *atr = 0;
int numChanged = json2.IntOf(L"numChanged");
wprintf(L"number of readers with a changed state: %d\n",numChanged);
i = 0;
count_i = json2.SizeOfArray(L"reader");
while (i < count_i) {
json2.put_I(i);
changed = json2.BoolOf(L"reader[i].changed");
if (changed == true) {
name = json2.stringOf(L"reader[i].name");
state = json2.stringOf(L"reader[i].state");
wprintf(L"Changed: \n");
wprintf(L" reader name: %s\n",name);
wprintf(L" new state: %s\n",state);
// If a card is now in this reader, we should have the ATR of the card..
if (json2.HasMember(L"reader[i].atr") == true) {
atr = json2.stringOf(L"reader[i].atr");
wprintf(L" ATR of card inserted into this reader: %s\n",atr);
}
}
i = i + 1;
}
// The output from the above loop:
// number of readers with a changed state: 1
// Changed:
// reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
// new state: present
// ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09
// Applications should always release the context when finished.
success = scard.ReleaseContext();
if (success == false) {
wprintf(L"%s\n",scard.lastErrorText());
}
}